The present invention relates to a locking assembly for a switch assembly. More particularly, the present invention relates to a locking assembly for an over-head hook-stick operated switch assembly. The locking assembly has a locking member that prevents an operating lever from closing a switch of the switch assembly.
Overhead electric power distribution lines are supported on utility poles having a height of up to 50 feet. Supports mounted to the pole often carry various electrical distribution lines. Because such electrical distribution lines commonly operate in a three-phase system with three lines mechanically connected to the horizontal support and electrically insulated from each other, three associated lines ordinarily must be switched and reconnected simultaneously for maintenance or rerouting of power in case of a fault. This simultaneous switching process requires a group operated switch system.
Currently, many high voltage switch assemblies for overhead power distribution lines are open and closed by a field technician using a hookstick. The hookstick engages an operating lever connected to a universal control section securely connected to the rotatable switch phase bearing. Rotation of the bearing is translated into lateral displacement of an interphase shaft along the horizontal support beam. Conductive switch blades on each switch phase connection may be rotated into or out of electrical connection with the respective phase line. Pulling a hook on the operating lever with the hookstick rotates the control shaft, which rotates the switch phases. Load interrupters suppress the formation of damaging arcs as the switch blades are opened.
High voltage overhead power switches are typically mounted well above ground and experience a variety of externally applied forces, such as weather, wild animals, vandalism, utility pole deformation, and vibration, that may cause a switch blade to move or close unintentionally. Furthermore, if a switch blade moves close enough to a contact, flashover may occur. The operating lever must maintain the security required to prevent unintended closing or movement of the conductive blades. Therefore, a need exists for an overhead switch assembly having a locking assembly to prevent accidental closing of the switch blades.
A typical phase group operated switch assembly installation includes at least one support beam mounted to an upright pole. The support beam supports the phases and conductor tension dead ending. Periodic inspection and maintenance is required to prevent against premature wear or damage to the switch assembly due to loss of proper adjustment caused by such adverse conditions as vibration, weathering of support components, wild animals, vandalism and dimensional changes in the utility pole (e.g., twisting). Accidental closing of the switch blades during a maintenance period may cause equipment damage, loss of electrical service and personnel injury. Therefore, a need exists for a locking assembly that clearly indicates to a person on the ground that the switches of the switch assembly are locked in an open position.
A need exists for a locking assembly for a hookstick operated switch assembly that secures a switch of the switch assembly in an open position to perform maintenance on the electrical system, while being removable to close the switch and return the electrical system to normal operating conditions.
Accordingly, it is a primary objective of the present invention to provide a locking assembly for a hookstick operated switch assembly to prevent unintentional movement and closing of a switch.
A further objective of the present invention is to provide a locking assembly that indicates to personnel on the ground that a switch of a switch assembly is in a locked open position.
The foregoing objects are basically attained by providing a hookstick operated switch assembly including a switch mounted to a support that is movable between open and closed positions. An operating lever is connected to the switch for opening and closing the switch. A locking arm is attached to the switch. A locking member is receivable by the locking arm when the switch is in the open position to prevent movement of the operating lever, thereby locking the switch in the open position.
When the locking member is received by the locking arm, movement of the operating lever is prevented, thereby ensuring that the switch blades do not move or close. Preventing movement of the operating lever also precludes electrical arcing from occurring should the switch blade be accidentally moved too close to an electrical contact of the switch. Additionally, the locking member may be brightly colored to indicate to personnel on the ground that the switch has been locked in an open position and not to remove the locking member until proper authorization has been received.
Other objects, advantages and salient features of the invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the invention.
Referring now to the drawings that form a part of the original disclosure:
FIG. 1 is a front elevational view of a horizontally mounted switch assembly in a closed position having a locking assembly according to a first embodiment of the present invention;
FIG. 2 is a front elevational view of a delta mounted switch assembly in a closed position having a locking assembly according to a first embodiment of the present invention;
FIG. 3 is a front elevational view of a vertically mounted switch assembly in a closed position having a locking assembly according to a second embodiment of the present invention;
FIG. 4 is a front elevational view of a phase-over-phase mounted switch assembly in a closed position having a locking assembly according to a third embodiment of the present invention;
FIG. 5 is a front elevational view of a locking assembly according to the first embodiment of the present invention connected to the horizontally mounted switch assembly of FIG. 1 in an open position;
FIG. 6 is a front elevational view of the locking arm of FIG. 5;
FIG. 7 is a bottom plan view of the locking arm of FIG. 5;
FIG. 8 is side elevational view of the locking arm of FIG. 5;
FIG. 9 is a top plan view of the locking arm assembly connected to the horizontally mounted switch assembly of FIG. 1;
FIG. 10 is a front elevational view of the locking arm assembly connected to the horizontally mounted switch assembly shown in FIG. 9;
FIG. 11 is a front elevational view of a locking assembly according to the third embodiment of the present invention connected to the vertically mounted switch assembly of FIG. 3 in an open position;
FIG. 12 is a front elevational view of the locking arm of FIG. 11;
FIG. 13 is a side elevational view of the locking arm of FIG. 12;
FIG. 14 is a front elevational view of a locking assembly according to the fourth embodiment of the present invention connected to the phase-over-phase mounted switch assembly of FIG. 4 in an open position;
FIG. 15 is a front elevational view of the locking arm of FIG. 14;
FIG. 16 is a top plan view of a first locking member for the locking assembly of the present invention;
FIG. 17 is a top plan view of a second locking member for the locking assembly of the present invention; and
FIG. 18 is a front elevational view of the second locking member of FIG. 17.